独柱双塔中央双索面半漂浮体系斜拉桥抗震分析

Seismic Analysis of Cable-stayed Bridge with Single-column and Double-tower Central Double Cable Plane Semi-floating System

独柱双塔中央双索面混凝土箱梁斜拉桥作为双线悬吊体系,常用于交通量日益增加且桥墩布置受限制的市政宽体桥梁中,但是该类桥梁主梁宽跨比较小,在地震多发的地区研究其抗震性能显得尤其重要。为研究该类斜拉桥的抗震性能,以主跨365 m的某大桥为例,采用MIDAS/Civil建立该桥空间有限元模型,分析了该桥在基础不考虑河水冲刷和考虑河水冲刷两种情况下的地震反应。分析结果表明,主梁关键截面轴力和剪力几乎不受冲刷的影响,但对截面的弯矩有一定影响;索塔塔顶位移、主梁梁端位移以及塔、梁端的相对位移受冲刷的影响均较小;在考虑最不利荷载组合时,各截面内力设计值均小于其承载能力值,满足设计要求。

The single-column and double-tower central double-span concrete box girder cable-stayed bridges that the width-span ratio of main girder is relatively small are used as a two-line suspension system for municipal wide-body bridges with increasing traffic volume and limited pier width, and research on the seismic performance in areas with frequent earthquakes is particularly important. In order to analyze the seismic performance of this kind of cable-stayed bridge, by taking a Bridge with 365 m main span as an example, MIDAS/Civil is used to establish the finite element model of the bridge space to analyze without considering river water erosion and considering river water erosion. The seismic response in the case shows that the axial force and shear force of the critical section are almost unaffected by the scouring, but have a certain influence on the bending moment of the section;the scouring have little impacts to the top displacement of the tower, the displacement of the main beam end and the relative displacement of the tower and beam ends is small;when considering the most unfavorable load combination, the internal force design values of each section are smaller than the bearing capacity value, which meets the design requirements.